A variety of systems and methods have been developed and used to detect and identify hazardous chemical and biological threat agents in the field. Chemical test kits that employ chemically reactive vapor-samplers and detection papers have long been used to detect chemical nerve agents, blood agents, and blister agents. While chemical kits are useful, they are designed to detect a limited range of conventional chemical agents that are toxic in the range of 10−3 g/person, provide no standoff protection and may be prone to false negative and positive detections.
Systems that employ Ion Mobility Spectrometry (IMS) in which molecules are ionized and separated according to their differences in velocities through a gas in the presence of an electric field can, in theory, identify and detect a wide variety of chemical and biological warfare (CBW) agents. IMS systems, however, require direct exposure to the chemical agent and the instruments typically have insufficient resolving power to identify CBW agents before they have reached casualty producing levels.
Other systems employ passive infrared (PIR) imaging to detect airborne chemical threats such as nerve (GA, GB, and GD) and blister (H and L) agents based on the infrared spectrum of the agent. Currently fielded devices have been reported to detect aerosols at a distance of up to 5 km. Practical PIR detection systems have difficulty detecting low levels of CBW surface target contaminants because the surfaces are typically at thermal equilibrium and provide insufficient contrast to identify target contaminants. Additionally, background radiation and interference encountered in the field can also make detection difficult.
What is needed is a system and method for use in the field that rapidly, reliably, and repeatably detects the presence or absence of a wide variety of surface target contaminants at very low levels and can be operated remotely at a safe distance in order to detect target contaminants before casualty producing concentrations are encountered. Embodiments according to the present invention address these needs, at least in part.
The following patents are incorporated herein by reference for background purposes as if fully set forth: U.S. Pat. No. 6,731,804, issued May 4, 2004 to Carrieri, et al; U.S. Pat. No. 5,241,179, issued Aug. 31, 1993 to Carrieri; U.S. Pat. No. 6,464,392, issued Oct. 15, 2002 to Carrieri, et al.; and U.S. Pat. No. 5,631,469 issued May 20, 1997 to Carrieri, et al.